The matrices we're using can produce very slightly out of range color
channels. This gives surprising results when in shader blending is used
for color burn and color dodge. After this change we clamp the RGB
values to 0..1 before applying premul.
Adds a GM modeled on a blink layout test that shows the problem using
SkImageMakeFromYUVAPixmaps.
Bug: skia:9619
Change-Id: I446d39763a7f5a2f7c5f61d94d163927d851baa3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/253879
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
